Alibaba is a good source to IDENTIFY potential suppliers, but then you really need to do your own investigation. This means at the very least many emails, even more skype chats, to see how available they are, what is their real level of English, as well as a few phone calls to talk in person. I absolutely recommend that you also visit and inspect your supplier in person.
Personally, I've had great experiences, but also bad (in some cases, I paid 5000$ - 50% of the transaction - and lost it all when they failed to ship anything at all). In that particular instance, it was from a supplier that I had met in person in China...
I also recommend you start with a small order, and slowly build the relationship, but I wouldn't put too much value in the gold supplier thing. I think they can just pay to have that. In my case, I even bought an official 3rd party audit document, and the document was raving about their abilities, but I suspect that the person I was talking to was not really working for that specific manufacture, just a reseller.
Also, keep in mind that in the case of a scam (which I experienced) your recourses are nil. Nobody at alibaba could care less, and they won't help you with anything.
So, it is a risk you need to take.. but if you are paying 20% of the local US price, it may be worth it. In my experience, despite the lost on one transaction, the net has been a positive one as I saved much more than I lost.
Also, take everything you are told with a grain of salt. For example, I purchase items that were supposedly "warranties for 2 years", but right when I received them, there were some issues with some lamps (didn't ship exactly the right model, problematic packaging) but they refused any sort of exchange or replacement. There is NO warranty - ever - in China.
Again, my advice:
- onsite visit if this is going to be a major supplier
Also, before transferring any money, I always require pictures of my items BEFORE they are packaging. It doesn't guarantee against a scam, but at least it can save you some trouble again someone who isn't reliable and was going to ship the wrong items, etc.